Question

1. Write a function flipSwitches that accepts one argument, a sequence of upper or lower case letters (the sequence can either be a str or a list, if you write your code correctly, it shouldn’t matter). This is a sequence of switches, uppercase means to turn a switch on, and lowercase to turn a switch off.   For example, ‘A’ means to turn the switch ‘A’ on, and ‘a’ means to turn the switch ‘A’ off.   (Turning an on switch on again, or an off switch off again, has no effect).   The function should then return the set of those switches that are still on at the end of the sequence of switches.   For example, the expression flipSwitches( ['A','A','a','B'] ) returns the set {'B'} because, the switch ‘B’ is turned on during the sequence, whereas the switch ‘A’ is turned on twice (so still on), then turned off once, so it is off at the end.   To receive full credit, your code must use a set that keeps track of the switches that are on. You can then iterate over the sequence and modify the set of switches that are on as appropriate. Sample output:

>>> flipSwitches( ['A','A','a','B'] )

{'B'}

>>> flipSwitches( 'ABCba')

{'C'}

>>> flipSwitches( 'sdfjSDSDFasjjfdjldsSDF' )=={'S', 'D', 'F'}

True

use python 3.7

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

#code

#required method
def flipSwitches(switches):
    #initializing an empty set to store switches that are on
    on_switches=set()
    #looping through each element/character in switches
    for i in switches:
        #checking if i is uppercase or lowercase
        if i.isupper():
            #simply adding i to on_switches. note that since on_switches is a set,
            #we dont have to worry about duplicates as duplicates are not allowed
            #in sets
            on_switches.add(i)
        elif i.islower():
            #converting i to upper case
            i=i.upper()
            #if i is in on_switches, removing it, meaning turning switch i off
            if i in on_switches:
                on_switches.remove(i)
    #at the end, returning on_switches set
    return on_switches